This study aims to explore biochemical changes in saliva during cardiorespiratory exercise using attenuated-total-reflectance-Fourier-transform-infrared-spectroscopy (ATR-FTIR). Saliva and blood samples were obtained from six athletes at rest, and after running at speeds of 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 kilometers-per-hour (km/h) on a treadmill (maximal stress test). Saliva ATR-FTIR spectra were analyzed using deconvolution and multivariate analysis. Area-under-the-curve calculations suggest differential changes in glucose, lactate, protein, lipids, carbohydrate and phosphate content in saliva during the test. Increases in glucose and lactate levels with increasing speeds were verified by simultaneous measurement of blood glucose and lactate levels using standard equipment (Roche®). Multivariate principal-component-analysis (PCA) showed discrete clusters for low (rest-14 km/h) and high (15 - 20 km/h) speeds, and PCA-linear-discriminant-analysis showed 100% classification of 18 - 20 km/h as high speed. Overall, results suggest the possibility of using this non-invasive saliva-based ATR-FTIR method for biochemical assessment during sports exercise and stress tests.
Keywords: ATR-FTIR; Maximal stress test; PCA-LDA; exercise associated biochemical changes; exercise related changes in saliva.